1. What are the important functions of the thyroid gland? Below the neck (neck) of each of us, there grows tissue like a butterfly (and like a defense shield in ancient warfare, in the shape of an H or U) called the thyroid gland (as shown in the picture), which consists of left and right lateral lobes located on either side of the trachea and an isthmus in the middle. It is the largest endocrine organ in the body. The main functions of the thyroid gland are to take up and store iodine, and to synthesize and secrete thyroid hormones. The main thyroid hormones are thyroxine (tetraiodothyronine, T4) and triiodothyronine (T3). The main function of thyroid hormones is to regulate the material and energy metabolism of the body. Thyroid hormones accelerate the oxidation process of cells throughout the body, promote the catabolism of proteins, lipids and carbohydrates, and increase the metabolic rate of the body. At the same time, it also plays an important role in promoting human growth and development, especially the growth and development of the bones and nervous system. There is also a kind of C cells in the interstitium of the thyroid gland, which can secrete calcitonin. 2.What factors affect the function of the thyroid gland? The functional activity of the thyroid gland is mainly regulated by the hypothalamus and pituitary systems, which form the hypothalamus, pituitary and thyroid axis. TSH secreted by the anterior pituitary gland directly excites the thyroid cells and promotes the secretion and synthesis of thyroid hormones. When the concentration of thyroid hormone in the blood increases to a certain extent, it inhibits the production of TSH (negative feedback), which slows down the synthesis and secretion of thyroid hormone; conversely, when the concentration of thyroid hormone in the blood decreases for various reasons, it can cause an increase in the secretion of TSH (feedback), which accelerates the synthesis and secretion of thyroid hormone.TSH secretion is also influenced by the hypothalamus thyrotropin-releasing hormone (TRH). releasing hormone (TRH). When the release of thyroid hormone increases, in addition to the inhibitory effect on the release of TSH from the pituitary gland, it also has an antagonistic effect on the release of TRH from the hypothalamus, indirectly inhibiting the secretion of TSH, thus maintaining the balance of the hypothalamus, pituitary, and thyroid axes. The thyroid gland also has adaptive regulation to iodine deficiency or iodine excess in the body, for example, when the inorganic iodine content in the blood is elevated, it can stimulate iodine uptake by the thyroid gland and its combination with tyrosine to produce more thyroxine, but when the inorganic iodine in the blood is accumulated to a critical value, it can cause the progressive inhibition of the combination of iodine and tyrosine and the reduction of the synthesis and release of thyroxine. The thyroid gland is controlled by the above regulatory systems to maintain normal growth, development and metabolic function. Thyroid function is also affected by drugs (dopamine, glucocorticoids, iodine, lithium carbonate, ketoconazole, propranolol, sex hormones, etc.) and diseases (liver disease, kidney disease, psychiatric disease, critical illness). 3. Can I see or feel the thyroid gland clearly under normal circumstances? The thyroid gland is one of the largest endocrine glands in the body. The thyroid gland weighs about 20~30g and is slightly larger in women. The size of the lateral lobes: 4~5cm long, 1~2cm wide and 2~3cm thick. the thyroid gland is wrapped by two layers of membranes: the inner intrinsic membrane and the outer surgical membrane. The thyroid gland is fixed to the trachea and cricoid cartilage by the surgical periosteum, and there are suspensory ligaments on the medial side of the upper pole of the right and left lobes that suspend the thyroid gland from the cricoid cartilage, so that the gland moves up and down with the swallowing maneuver. Under normal circumstances, the thyroid gland cannot be clearly seen or felt. 4.How much iodine does a normal person need to consume daily? The minimum physiological requirement of iodine for a normal adult is 75 μg/d. WHO recommends a daily iodine intake of 150 μg for adults, 70 μg for those under 4 years of age, and 200 μg for pregnant women and lactating mothers. Under normal physiological conditions, the iodine excreted is equal to the iodine ingested. Urinary iodine below 150ug/L indicates iodine deficiency, and above 300ug/L indicates iodine overdose, which is harmful to the thyroid gland. 5. How much thyroid hormone is secreted by the thyroid gland in normal adults? Every day, the thyroid gland secretes 0.5~1% (about 100?) of the stored thyroid hormone into the blood, and the T4 secreted into the blood is about 30 times of the T3, and all of the T4 in the blood comes from the thyroid gland, while about 20% of the T3 in the blood originates from the thyroid gland, and 80% of the blood originates from the T3 converted from the T4 of the peripheral tissues. 99% of the thyroxine in the blood combines with the proteins, and less than 1% of it is free. The half-life of T4 is about 7 days, and that of T3 is 1.5 days; the biological activity of T3 is about 5 times greater than that of T4. 6.Why does the thyroid bleed easily during surgery or injury? The thyroid gland has a very rich blood supply with paired superior and inferior thyroid arteries and sometimes the lowermost thyroid artery. Both the superior and inferior thyroid arteries have branches that anastomose with each other at the upper and lower thyroid glands, as well as with the arterial branches of the larynx, trachea, pharynx, and esophagus, forming a rich vascular network. Therefore, after major resection of the thyroid gland, although the upper and lower thyroid arteries on both sides are ligated, ischemia of the residual thyroid gland or parathyroid glands is unlikely to occur. The thyroid veins are highly variable, with three main pairs of veins, the superior, middle, and inferior thyroid veins. The thyroid gland is one of the organs with the richest blood supply, and blood flow is extremely rapid, with a blood flow of 4-6 ml/min per gram of thyroid tissue, and about 100-150 ml/min through the entire thyroid gland. In patients with diffuse goiter with hyperthyroidism (Graves’ disease, Graves’ disease), the blood flow can increase to 1000 ml/min, so that tremors and vascular murmurs can be detected in the neck. Because of the rich blood circulation of the thyroid gland, it is easy to bleed during thyroid surgery or injury. 7.What are the functions of parathyroid glands? What are the manifestations after injury? There are 4 parathyroid glands attached to the gap between two layers of peritoneum at the back of two lobes of the thyroid gland. The parathyroid glands secrete parathyroid hormone, which regulates the metabolism of calcium and phosphorus in the body and maintains the balance of blood calcium and phosphorus. If the parathyroid glands are mistakenly injured or removed, the secretion of parathyroid hormone will decrease and the blood calcium concentration will fall, which will cause the patient to be nervous, anxious and tense. The incidence in tertiary hospitals is usually less than 2%. 8.Why does hoarseness occur after thyroid surgery? The nerves near the thyroid gland mainly include the superior laryngeal nerve and the recurrent laryngeal nerve, both of which originate from the vagus nerve. The superior laryngeal nerve has internal and external branches. The internal branch is a sensory branch, distributed in the larynx and epiglottis mucosa, if damaged, it can lead to the disappearance of epiglottic reflex and choking on drinking water; the external branch is a motor branch, which is close to the supra-thyroid artery and distributed in the cricothyroid muscle, if damaged, it can lead to the paralysis of the cricothyroid muscle, which can cause the vocal cords to be relaxed and the voice to be lowered. The recurrent laryngeal nerve in the neck is located in the tracheoesophageal groove on the dorsal side of the thyroid gland, and it innervates the movement of the vocal cords. The injury rate of the recurrent laryngeal nerve in thyroid surgery has been less than 2% in tertiary hospitals. Laryngeal recurrent nerve injury is divided into two categories: temporary and permanent. If the laryngeal recurrent nerve is ligated or cut off during surgery, it will cause permanent paralysis of the vocal cords, and the hoarseness of the voice is also permanent. If only mild intraoperative pulling, or postoperative edema, hematoma compression of the laryngeal nerve, hoarseness is mostly temporary, edema subsides, hematoma lifted, within six months the laryngeal nerve function can generally be restored, hoarseness phenomenon can disappear. Most of the hoarseness after thyroid surgery is caused by the latter. If bilateral laryngeal recurrent nerve injury can appear dyspnea or asphyxia. 9. What are the thyroid diseases? Thyroid disorders can be divided into four main categories: hyperthyroidism (hyperthyroidism), hypothyroidism (hypothyroidism), thyroiditis, and thyroid nodules. Hyperthyroidism: the incidence rate is about 3%, with an increasing trend in recent years. According to the etiology, Graves’ disease (toxic diffuse goiter) accounts for 70%-85%, thyroiditis accounts for 5%-25%, toxic nodular goiter accounts for 5%-15%, toxic adenomas accounts for 3%-30%, and medical origin, thyroid carcinoma and ectopic secretion are rare. Hypothyroidism: According to the etiology, there are primary hypothyroidism, transient hypothyroidism (subacute thyroiditis, postpartum thyroiditis, painless thyroiditis), secondary hypothyroidism (pituitary or hypothalamus lesions) and systemic thyroid hormone resistance syndrome. Thyroiditis: subacute thyroiditis, chronic lymphocytic thyroiditis (Hashimoto’s disease, Hashimoto’s thyroiditis), postpartum thyroiditis, and painless thyroiditis are common according to etiology. Thyroid nodules: the incidence rate is about 3%, with an increasing trend in recent years. The etiology of thyroid nodules is divided into two categories: benign and malignant. Including many middle thyroid diseases, benign thyroid nodules include: hyperplastic goiter (diffuse and nodular), toxic nodular goiter, thyroid adenoma, thyroid cyst, focal thyroiditis, etc. Malignant thyroid nodules include differentiated thyroid carcinoma (papillary thyroid carcinoma, follicular thyroid carcinoma, medullary carcinoma) and undifferentiated thyroid carcinoma, and metastatic thyroid carcinoma is extremely rare. Differentiated thyroid cancer accounts for the majority (99%), and the prognosis is good with timely and proper treatment. 10.How to arrange diet for hyperthyroid patients? The metabolism of patients with hyperthyroidism is more vigorous than normal, and the energy consumption is more than normal, so the patients with hyperthyroidism should be provided with more nutritious diets. The general dietary principle is to rationalize the diet, give high calorie, high protein, high vitamin and low iodine diet. Eat more meat, eggs, beans and fresh vegetables. Do not eat seafood, such as fish, shrimp, kelp, seaweed, nori and shellfish from the sea when you start medication. Don’t eat iodine-containing drugs, such as Wassail tablets, during treatment, and don’t use iodine contrast media. Some people think that hyperthyroidism needs to eat more kelp or limit the high nutritional diet is wrong, and there is no scientific basis. 11.Why does hypothyroidism occur with radioactive iodine treatment for hyperthyroidism? Radiation iodine (131I) treatment of hyperthyroidism has a history of nearly 70 years, since 1958, China began to use 131I treatment of hyperthyroidism, so far has cured more than 200,000 people. It is now recognized that 131I treatment of hyperthyroidism is a safe, simple and effective treatment, and it has become the preferred treatment for hyperthyroidism in Europe and the United States. It is also recognized that hypothyroidism is an unavoidable complication and result of 131I treatment of hyperthyroidism, and the incidence of hypothyroidism has been reported to increase by 5% per year in foreign countries, to reach 30% in 5 years, and to reach 40-70% in 10 years. The incidence of early-onset hypothyroidism is reported to be about 10% in China, and late-onset hypothyroidism reaches 59.8%. So whether to choose 131I treatment of hyperthyroidism is mainly to weigh the pros and cons of the consequences of hyperthyroidism and hypothyroidism. 131I treatment of hyperthyroidism why will happen hypothyroidism? 12. Hypothyroidism occurring in the treatment of hyperthyroidism is divided into early-onset hypothyroidism (within 1 year of 131I treatment) and late-onset hypothyroidism (1 year after 131I treatment) according to the time of occurrence. Early-onset hypothyroidism occurs 2-6 months after 131I treatment and is characterized by chills, swelling, fatigue, abdominal distension, etc. T3 and T4 are decreased and TSH is increased. The cause of early-onset hypothyroidism is still not very clear, and some studies have confirmed that it is related to factors such as 131I dose and individual sensitivity. The cause of late-onset hypothyroidism is still unclear, some scholars believe that it is related to the 131I dose, and some believe that it is not related to the dose. Because of the occurrence of hypothyroidism can be used L-T4 replacement therapy, so that the thyroid function to maintain normal, work, life and learning are not affected, women of childbearing age can be normal pregnancy and childbirth, so the 131I treatment of hyperthyroidism hypothyroidism do not need to fear.